How Can I Overload the `operator[]` with Multiple Arguments in C ?

Operator[] with Multiple Arguments in C

You may encounter difficulties when attempting to define an array operator in C that takes multiple arguments. Using the following syntax:

const T& operator[](const int i, const int j, const int k) const {
    return m_cells[k*m_resSqr+j*m_res+i];
}

T& operator[](const int i, const int j, const int k) {
    return m_cells[k*m_resSqr+j*m_res+i];
}

You will receive an error message:

error C2804: binary operator '[' has too many parameters

Workaround (Pre-C 23)

Prior to C 23, overloading operator[] with multiple arguments was not possible. Instead, you can overload operator().

Resolution (C 23)

However, from C 23 onwards, you can overload operator[] directly. This is demonstrated in the cppreference example below:

struct V3
{
    double x, y, z;

    constexpr V3 operator[](int i) const {
        return { x, y, z }[i];
    }

    // Alternatively, using std::initializer_list:
    friend constexpr std::initializer_list<double> operator()(const V3& v) {
        return { v.x, v.y, v.z };
    }
};

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